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Bio Psych Topics 1 - 4, Responsible for quick acting reflexes
Uses…
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- Responsible for quick acting reflexes
- Uses neurons in order to do so, consisting of sensory, relay and motor
- Involuntary response to environmental stressors
- Responsible for regulation and control of internal organs
- Restores normal physiological functioning.
- 'Rest and Digest'
- Release of acetylcholine
- Responsible for preparing body for 'fight or flight'
- Releases adrenaline into bloodstream which increases heart rate and as such, oxygen supplied to muscles
- In response to sudden stressors, the Sympathetic division of the nervous system is triggered.
The following process is known as the SAM pathway in which;
- Sympathetic nervous system prepares body for fight or flight
- to do this adrenaline is needed and so, the sympathetic nervous system sends a signal to the adrenal medulla to release adrenaline. Which causes heart to beat faster
- the final step of this pathway is the activation of the Parasympathetic nervous system. The parasympathetic nervous system restores normal physiological functioning to body
If the brain continues to perceive a threat, a second system kicks in. As the initial surge of adrenaline subsides, the hypothalamus activates the HPA axis;
- Hypothalamus releases chemical messenger CRH which enters bloodstream
- CRH stimulates pituitary gland to produce and secrete ACTH which enters the bloodstream and is transported in the blood stream to it's target
- ACTH then arrives at the adrenal cortex and causes it to release cortisol.
Cortisol
causes several affects in the body that are important to the fight or flight response;positives
- quick burst of energy
- higher pain threshold
negatives (over time)
- impaired cognitive performance
- lowered immune response
- Transfer signal from sensory neurons to motor neurons.
- Lie wholly within spinal cord and brain
- Convert energy from receptors into electrical impulse.
- Impulse runs from dendrites to axon terminal
- Receive impulse from intermediate neuron
- Carry impulses to effector (often a muscle or gland)
- Consist of dendrites, a cell body and an axon
- Motor and sensory neurons can be myelinated to decrease speed of transmission
- Action potential arrives at presynaptic neuron
- Causes synaptic vesicles to migrate toward presynaptic membrane
- Synaptic vesicles fuse with membrane and release contents into synaptic cleft
- Neurotransmitters diffuse across synaptic cleft toward postsynaptic membrane
- At postsynaptic membrane, neurotransmitters bind to receptors within membrane
- Whether or not postsynaptic neuron will 'fire' depends on summation
Neurotransmitters can be excitatory or inhibitory.
Excitatory neurotransmitters like acetylcholine and noradrenaline increase the chance a neuron will fire
Inhibitory neurotransmitters like serotonin or GABA decrease the chance a neuron will fire
If excitatory postsynaptic potential is greater than inhibitory postsynaptic potential neuron will be more likely to fire
If inhibitory postsynaptic potential is greater than excitatory postsynaptic potential neuron will be less likely to fire
If EPSPs and IPSPs are received at the same time, it is the summation of these 2 potentials that determines how likely it is that the neuron will fire. This is determined by both spatial and temporal summation.
- produce and secrete specific hormones
- chemical messengers that travel in the bloodstream to specific target cells or organs, where they bind to complementary changes and cause physiological response
- operate under negative feedback which prevents levels of hormones from becoming too high
- release hormones whose function is to stimulate release of more hormones
- controlled by the hypothalamus
- anterior pituitary releases FSH and LH.
- posterior pituitary releases oxytocin